Add offline news and updates to home page

docs/news.md

@@ -0,0 +1,3 @@
+# News & Updates
+
+Welcome to NoteBookmark! Check back here for product updates.

src/NoteBookmark.MauiApp.Tests/NewsFeedServiceTests.cs

@@ -0,0 +1,185 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Net.Http;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.Extensions.Logging;
+using NoteBookmark.MauiApp.Data;
+
+namespace NoteBookmark.MauiApp.Tests;
+
+public sealed class NewsFeedServiceTests : IDisposable
+{
+    private readonly string _appDataDirectory = Path.Combine(Path.GetTempPath(), $"NoteBookmark-News-{Guid.NewGuid():N}");
+
+    [Fact]
+    public async Task RefreshAsync_CachesMarkdownAndReferencedImagesForOfflineRendering()
+    {
+        var handler = new StubHttpMessageHandler(request =>
+        {
+            if (request.RequestUri!.AbsolutePath.EndsWith("/docs/news.md", StringComparison.Ordinal))
+            {
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent("# Updates\n\n![Logo](assets/logo.png)\n\n[Unsafe](javascript:alert(1))", Encoding.UTF8, "text/plain")
+                };
+            }
+
+            if (request.RequestUri.AbsolutePath.EndsWith("/docs/assets/logo.png", StringComparison.Ordinal))
+            {
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new ByteArrayContent(new byte[] { 1, 2, 3 })
+                };
+            }
+
+            return new HttpResponseMessage(HttpStatusCode.NotFound);
+        });
+        var service = CreateService(handler);
+
+        await service.RefreshAsync();
+        var html = await service.GetHtmlAsync();
+
+        html.Should().Contain("<h1>Updates</h1>");
+        html.Should().Contain("src=\"data:image/png;base64,AQID\"");
+        html.Should().Contain("href=\"#\"");
+        File.Exists(Path.Combine(_appDataDirectory, "docs", "news.md")).Should().BeTrue();
+        File.Exists(Path.Combine(_appDataDirectory, "docs", "assets", "logo.png")).Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task GetHtmlAsync_WhenNoFeedIsCached_LoadsRemoteFeed()
+    {
+        var handler = new StubHttpMessageHandler(_ => new HttpResponseMessage(HttpStatusCode.OK)
+        {
+            Content = new StringContent("# Online feed", Encoding.UTF8, "text/plain")
+        });
+        var service = CreateService(handler);
+
+        (await service.GetHtmlAsync()).Should().Contain("<h1>Online feed</h1>");
+        File.Exists(Path.Combine(_appDataDirectory, "docs", "news.md")).Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task RefreshAsync_WhenRemoteRefreshFails_KeepsCachedFeed()
+    {
+        var requestCount = 0;
+        var handler = new StubHttpMessageHandler(_ =>
+        {
+            requestCount++;
+            if (requestCount == 1)
+            {
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent("# Existing feed", Encoding.UTF8, "text/plain")
+                };
+            }
+
+            throw new HttpRequestException("Network unavailable.");
+        });
+        var service = CreateService(handler);
+        await service.RefreshAsync();
+
+        var act = () => service.RefreshAsync();
+        await act.Should().ThrowAsync<HttpRequestException>();
+        (await service.GetHtmlAsync()).Should().Contain("<h1>Existing feed</h1>");
+    }
+
+    [Fact]
+    public async Task GetHtmlAsync_WhenNoFeedIsCached_ReturnsFriendlyFallback()
+    {
+        var service = CreateService(new StubHttpMessageHandler(_ => new HttpResponseMessage(HttpStatusCode.NotFound)));
+
+        (await service.GetHtmlAsync()).Should().Contain("Welcome to NoteBookmark");
+    }
+
+    [Fact]
+    public async Task RefreshAsync_CachesReferenceStyleImagesAndPathsWithParentheses()
+    {
+        var service = CreateService(CreateFeedHandler(
+            "# Updates\n\n![Logo][logo]\n\n![Chart](assets/chart(1).png)\n\n[logo]: assets/logo.png",
+            "/docs/assets/logo.png",
+            "/docs/assets/chart%281%29.png"));
+
+        await service.RefreshAsync();
+        var html = await service.GetHtmlAsync();
+
+        html.Should().NotContain("assets/");
+        html.Should().Contain("src=\"data:image/png;base64,AQID\" alt=\"Logo\"");
+        html.Should().Contain("src=\"data:image/png;base64,AQID\" alt=\"Chart\"");
+        File.Exists(Path.Combine(_appDataDirectory, "docs", "assets", "logo.png")).Should().BeTrue();
+        File.Exists(Path.Combine(_appDataDirectory, "docs", "assets", "chart(1).png")).Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task RefreshAsync_IgnoresImageSyntaxInsideCodeBlocks()
+    {
+        var service = CreateService(CreateFeedHandler(
+            "# Updates\n\n```markdown\n![Example](assets/missing.png)\n```\n\n`![Inline](assets/also-missing.png)`"));
+
+        await service.RefreshAsync();
+        var html = await service.GetHtmlAsync();
+
+        html.Should().Contain("![Example](assets/missing.png)");
+        Directory.Exists(Path.Combine(_appDataDirectory, "docs", "assets")).Should().BeFalse();
+    }
+
+    [Fact]
+    public async Task RefreshAsync_RaisesFeedUpdatedOnlyAfterSuccessfulRefresh()
+    {
+        var fail = false;
+        var handler = new StubHttpMessageHandler(_ => fail
+            ? throw new HttpRequestException("Network unavailable.")
+            : new HttpResponseMessage(HttpStatusCode.OK) { Content = new StringContent("# Feed", Encoding.UTF8, "text/plain") });
+        var service = CreateService(handler);
+        var updates = 0;
+        service.FeedUpdated += (_, _) => updates++;
+
+        await service.RefreshAsync();
+        fail = true;
+        var act = () => service.RefreshAsync();
+
+        await act.Should().ThrowAsync<HttpRequestException>();
+        updates.Should().Be(1);
+    }
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_appDataDirectory))
+        {
+            Directory.Delete(_appDataDirectory, recursive: true);
+        }
+    }
+
+    private NewsFeedService CreateService(HttpMessageHandler handler)
+    {
+        var logger = new Mock<ILogger<NewsFeedService>>();
+        return new NewsFeedService(new HttpClient(handler), logger.Object, _appDataDirectory);
+    }
+
+    private static StubHttpMessageHandler CreateFeedHandler(string markdown, params string[] assetPaths) =>
+        new(request =>
+        {
+            var path = request.RequestUri!.AbsolutePath;
+            if (path.EndsWith("/docs/news.md", StringComparison.Ordinal))
+            {
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent(markdown, Encoding.UTF8, "text/plain")
+                };
+            }
+
+            return Array.Exists(assetPaths, assetPath => path.EndsWith(assetPath, StringComparison.Ordinal))
+                ? new HttpResponseMessage(HttpStatusCode.OK) { Content = new ByteArrayContent(new byte[] { 1, 2, 3 }) }
+                : new HttpResponseMessage(HttpStatusCode.NotFound);
+        });
+
+    private sealed class StubHttpMessageHandler(Func<HttpRequestMessage, HttpResponseMessage> responseFactory) : HttpMessageHandler
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) =>
+            Task.FromResult(responseFactory(request));
+    }
+}

src/NoteBookmark.MauiApp.Tests/NoteBookmark.MauiApp.Tests.csproj

@@ -38,6 +38,8 @@
     <Compile Include="..\NoteBookmark.MauiApp\Data\LocalHtmlStorageService.cs" Link="Data\LocalHtmlStorageService.cs" />
     <Compile Include="..\NoteBookmark.MauiApp\Data\StorageService.cs" Link="Data\StorageService.cs" />
     <Compile Include="..\NoteBookmark.MauiApp\Data\SyncService.cs" Link="Data\SyncService.cs" />
+    <Compile Include="..\NoteBookmark.MauiApp\Data\INewsFeedService.cs" Link="Data\INewsFeedService.cs" />
+    <Compile Include="..\NoteBookmark.MauiApp\Data\NewsFeedService.cs" Link="Data\NewsFeedService.cs" />
     <Compile Include="..\NoteBookmark.MauiApp\Data\SyncApiClient.cs" Link="Data\SyncApiClient.cs" />
     <Compile Include="..\NoteBookmark.MauiApp\Data\MauiUrlLauncher.cs" Link="Data\MauiUrlLauncher.cs" />
   </ItemGroup>

src/NoteBookmark.MauiApp.Tests/SyncServiceTests.cs

@@ -19,6 +19,7 @@ public class SyncServiceTests
     private readonly Mock<ILocalDataService> _localDataServiceMock;
     private readonly Mock<ILogger<SyncService>> _loggerMock;
     private readonly Mock<ILocalHtmlStorageService> _localHtmlStorageServiceMock;
+    private readonly Mock<INewsFeedService> _newsFeedServiceMock;
     private readonly SyncService _sut;
 
     public SyncServiceTests()
@@ -27,13 +28,15 @@ public SyncServiceTests()
         _localDataServiceMock = new Mock<ILocalDataService>();
         _loggerMock = new Mock<ILogger<SyncService>>();
         _localHtmlStorageServiceMock = new Mock<ILocalHtmlStorageService>();
+        _newsFeedServiceMock = new Mock<INewsFeedService>();
 
         _apiClientMock.Setup(c => c.GetNote(It.IsAny<string>())).ReturnsAsync((Note?)null);
         _apiClientMock.Setup(c => c.GetPostHtmlAsync(It.IsAny<string>())).ReturnsAsync((string?)null);
         _localDataServiceMock.Setup(c => c.GetPostsAsync()).ReturnsAsync(new List<Post>());
         _localHtmlStorageServiceMock.Setup(s => s.GetCachedPostIds()).Returns(new List<string>());
+        _newsFeedServiceMock.Setup(s => s.RefreshAsync()).Returns(Task.CompletedTask);
 
-        _sut = new SyncService(_apiClientMock.Object, _localDataServiceMock.Object, _loggerMock.Object, _localHtmlStorageServiceMock.Object);
+        _sut = new SyncService(_apiClientMock.Object, _localDataServiceMock.Object, _loggerMock.Object, _localHtmlStorageServiceMock.Object, _newsFeedServiceMock.Object);
 
         SyncService.ClearInMemoryPreferences();
     }
@@ -249,6 +252,19 @@ public async Task SyncAsync_ShouldNotRunConcurrently()
         _localDataServiceMock.Verify(c => c.GetPendingSyncNotesAsync(), Times.Once);
     }
 
+    [Fact]
+    public async Task SyncAsync_ShouldRefreshNewsFeed()
+    {
+        _localDataServiceMock.Setup(c => c.GetPendingSyncPostsAsync()).ReturnsAsync(new List<Post>());
+        _localDataServiceMock.Setup(c => c.GetPendingSyncNotesAsync()).ReturnsAsync(new List<Note>());
+        _apiClientMock.Setup(c => c.GetPostsModifiedAfter(It.IsAny<DateTime>())).ReturnsAsync(new List<PostL>());
+        _apiClientMock.Setup(c => c.GetNotesModifiedAfter(It.IsAny<DateTime>())).ReturnsAsync(new List<Note>());
+
+        await _sut.SyncAsync();
+
+        _newsFeedServiceMock.Verify(s => s.RefreshAsync(), Times.Once);
+    }
+
     [Fact]
     public async Task PullPhase_ShouldDeleteLocalPosts_WhenDeletedOnServer()
     {

src/NoteBookmark.MauiApp/Components/Pages/Home.razor

@@ -1,27 +1,48 @@
 @page "/"
 @inject IAuthService AuthService
 @inject NavigationManager Nav
+@inject NoteBookmark.MauiApp.Data.INewsFeedService NewsFeed
 @implements IDisposable
 
 <div class="home-container">
     <h2>Hello, @(AuthService.Username ?? "there")!</h2>
     <p>You are signed in to NoteBookmark.</p>
+
+    <section class="news-section" aria-labelledby="news-heading">
+        <h3 id="news-heading">News &amp; Updates</h3>
+        <div class="news-content">@((MarkupString)newsHtml)</div>
+    </section>
 </div>
 
 @code {
+    private string newsHtml = "<p>Welcome to NoteBookmark! Check back here for product updates.</p>";
+
     protected override void OnInitialized()
     {
-        // No-op
+        NewsFeed.FeedUpdated += OnFeedUpdated;
+    }
+
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (!firstRender)
+        {
+            return;
+        }
+
+        await LoadNewsAsync();
     }
 
-    private async Task LogoutAsync()
+    // Sync refreshes the feed on a background thread, so marshal the reload back to the renderer.
+    private void OnFeedUpdated(object? sender, EventArgs e) => _ = InvokeAsync(LoadNewsAsync);
+
+    private async Task LoadNewsAsync()
     {
-        await AuthService.LogoutAsync();
+        newsHtml = await NewsFeed.GetHtmlAsync();
+        StateHasChanged();
     }
 
     void IDisposable.Dispose()
     {
-        // Cleanup resources if needed
+        NewsFeed.FeedUpdated -= OnFeedUpdated;
     }
 }
-

src/NoteBookmark.MauiApp/Data/INewsFeedService.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Threading.Tasks;
+
+namespace NoteBookmark.MauiApp.Data;
+
+public interface INewsFeedService
+{
+    /// <summary>Raised after a refresh has downloaded and cached a new copy of the feed.</summary>
+    event EventHandler? FeedUpdated;
+
+    Task RefreshAsync();
+    Task<string> GetHtmlAsync();
+}